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Physicists Inch Closer to Proof of Elusive Particle

Like Moses seeing the Promised Land but not being able to go there, Fermilab physicists said Monday that its Tevatron, now shuttered but once the world’s most powerful physics machine, had fallen just short of finding a long-hypothesized particle.

Known as the Higgs boson, it explains why things in the universe have mass, and is a cornerstone of modern physics despite never being seen.

The news from the Fermi National Accelerator Laboratory added more buzz and hype about the long-sought particle as physicists and many others are standing by for an announcement on Wednesday from CERN, the European Organization for Nuclear Research, home of the Large Hadron Collider, which supplanted the Tevatron as the big horse in physics, and whose physicists might be on the verge of announcing that they have actually found the Higgs boson.

On Monday, Fermilab, in Batavia, Ill., said its results were the best “indication” so far that the legendary particle exists.

In what amounts to a last hurrah for the Tevatron, Fermilab physicists said that when they combined the data from some 500 trillion collisions of protons and antiprotons recorded since 2001 there was a suspicious excess, a broad bump in the mass range between 115 billion electron volts and 135 billion electron volts, in the units physicists use to measure mass and energy.

The odds that the Fermilab bump were due to chance were only one in 550, they said. “This is very, very low number for all practical reasons, so I have strong confidence that beautiful theory developed by theorists almost 50 years ago is indeed how the Nature works,” wrote a Fermilab physicist, Dmitri Denisov.

Unfortunately, that is just shy of the one part in 770, or “3-sigma” in physics jargon, that is required to use the word “evidence,” let alone “discover,” leaving the Tevatron unable to settle the question of the elusive boson.

Instead the stage has been cleared for CERN. The discovery of a new fundamental constituent of nature, as the Higgs would be, is a once-in-a-generation event and the imminent discovery of the Higgs at CERN, outside Geneva, has thrown physicists into a frenzy of rumor and speculation. The five living founders of the Higgs theory have been invited to a news conference there, heightening expectations that something big is in the offing.

The boson is named for Peter Higgs of the University of Edinburgh, one of six physicists who envisioned a kind of cosmic molasses, now known as the Higgs field, that would impart mass to formerly massless particles trying to move through it like a celebrity trying to get to the bar. Physicists have been searching for the boson since the 1970s.

Correction: July 4, 2012

An article on Tuesday about an announcement by Fermilab physicists that the Tevatron accelerator had fallen just short of finding the elusive subatomic particle known as the Higgs boson misstated the odds of an event’s happening by chance that are required for particle physicists to use the word “evidence” in describing that event — a standard known as “3-sigma.” The 3-sigma standard corresponds to one part in 770, not one part in 3,000.

A version of this article appears in print on July 3, 2012, on Page A11 of the New York edition with the headline: Physicists Inch Closer to Proof of Particle. Order Reprints|Today's Paper|Subscribe